As an important part of a new generation of information technology, the internet of things (IOT) refers to a network in which information of the physical world is obtained through deploying various devices having capabilities of certain sense, computation, execution and communication, information transmission, collaboration and processing are realized through the internet, and thereby the interconnections between people and things, and between things and things are achieved. Generally, the first phase of the internet of things is called machine to machine (M2M), i.e., to realize free communication between machines. As for a communication network (such as the mobile cellular network), the type of communication service undertaken by the communication network is called a machine type communication (MTC).
In recent years, the long term evolution (LTE) project is the biggest new technology research and development project launched by the 3rd generation partnership project (3GPP), this kind of technology with the orthogonal frequency division multiplexing technology (OFDM)/the multi-input multi-output technology (MIMO) as the core can provide peak rates of downlink 100 Mbps and uplink 50 Mbps on a 20 MHz spectrum bandwidth, and can improve cell-edge user performance, increase cell capacity and reduce system delay. The performance advantages of the LTE system bring a great deal of benefits, presently, a number of M2M devices can make full use of the advantages of the LTE network, where, one type of M2M devices can bring immediate performance improvement by utilizing the characteristics of high speed and low delay characteristics of the LTE, and the other type of M2M devices is less demanding on connection.
Research on LTE-based low-cost MTC user equipment mainly considers the needed enhancement or optimization for the LTE network and air interfaces aimed at the introduction of MTC devices, where the coverage problem is one of the key issues concerned by operators. For example, an important application of the MTC user equipment is the intelligent instrument which is installed in the basement under the building, or is segregated by the metal shell. In this case, an MTC user equipment will undergo more severe path loss than a common user equipment, for example, the path loss increases 20 dB additionally. The severe path loss will make the power consumption of the MTC user equipment increase. Moreover, in consideration of the fact that the MTC user equipment are usually powered by a battery, the increasing of the power consumption will shorten the battery life, which is not good for equipment maintenance.